1. Field of the Invention
This invention relates generally to regional anesthesia and more particularly to an apparatus and procedure for nerve stimulator needle guidance in conjunction with various procedures, such as, the administration of an anesthetic blockade, neuro monitoring, electromyography and therapeutic intervention.
2. Antecedents of the Invention
The field of regional anesthesia relates to the practice of administering anesthesia to a specific body region during surgery, for the relief of postoperative pain, and for extended relief of trauma or chronic pain. Often, regional anesthesia has been found to be preferable to general anesthesia because of increased safety, the availability of postoperative pain control and decreased anesthetic costs.
Regional anesthesia delivery techniques strove to optimize administration of a local anesthetic in close proximity to a target or nerve plexus so as to establish a neural blockade. Successful administration of regional anesthesia was dependent upon the accurate placement of the anesthetic in relation to the target nerve or nerves.
Various techniques have been employed to assist in placement of an administration needle in close proximity to the target nerve which was not externally visible. One of the traditional methods of needle placement involved eliciting paresthesia. Among the disadvantages of this technique was the lack of accurate patient responses amongst patients who were disoriented and/or sedated.
A prevalent technique employed the use of nerve stimulators electrically coupled to a nerve stimulator needle. Such method was premised upon the phenomenon that an electrical pulse is capable of stimulating a motor nerve fiber to contract an innervated muscle or cause paraesthesia, in the case of sensory nerve stimulation.
Nerve stimulators generally comprised a power supply, a pulse generating circuit and current adjusting means, e.g. the DIGISTIM III nerve stimulator sold by Neuro Technology Inc. of Houston, Tex., coupled to insulated or uninsulated anesthesia needles. U.S. Pat. No. 4,515,168, issued to CHESTER illustrates a nerve stimulator which mounts directly upon a syringe and needle.
Suggested improvements in techniques of utilizing nerve stimulator needles have been exemplified by the patents to GRIFFITH (U.S. Pat. No. 5,853,373), HADZIC (U.S. Pat. No. 5,830,151), RAYMOND (U.S. Pat. No. 5,248,153) and CHESTER (U.S. Pat. No. 4,515,168), which were directed to avoiding the requirement for the presence of an assistant in order to reduce the current levels as the needle was advanced toward the target nerve or nerve plexus.
The nerve stimulator needle, e.g. a CONTIPLEX nerve block set sold by B. Braun Medical, Inc. of Bethlehem, Pa., was placed within the tissue of the patient""s body in the vicinity of the nerve to be blocked and then advanced until stimulation of the target nerve was achieved as determined by visually detecting muscle contractions or by eliciting a report that the patient felt the stimulus in response to the current flow through the stimulator needle.
The current supplied by the nerve stimulator was reduced as the nerve stimulator needle was further advanced, until stimulation of the target nerve was achieved using a reduced current level associated with a prescribed distance between the needle tip and the target nerve.
Thereafter, a portion of the anesthetic dose was administered through the needle to terminate the response to the nerve stimulation current. If the response was terminated by the initial administration, the needle was deemed to be properly positioned in proximity to the target nerve and the remaining dose of anesthetic was administered.
It should be understood, however, that the initial placement of the needle was dependent upon anatomic landmarks. Since anatomic landmarks varied from patient to patient, they constituted only an approximate starting zone or region to guide needle insertion. Successful administration was often dependent upon the skill and experience of the anesthesiologist. Multiple needle passes were required when the initial needle placement was not directly registered over the target nerve or nerve plexus or when the angle of introduction was anatomically incorrect.
Peripheral nerves have been stimulated with cutaneous electrodes at appropriate landmarks utilizing a coupling gel for monitoring the degree of neuromuscular blockade during general anesthesia when neuromuscular relaxing or paralyzing drugs were intravenously administered.
A nerve stimulator needle guidance system includes a cutaneous electrode having a conductive tip at the end of a cylindrical body with a bore extending coaxially through the body and tip.
The cutaneous electrode is coupled to a nerve stimulator to locate a target nerve registration point while depressing the patient""s dermal layers. Thereafter a nerve stimulator needle, coupled to the nerve stimulator, is introduced into the patient at the located registration point through the bore. Conventional nerve stimulation techniques are employed to properly position the needle tip adjacent to the target nerve for the administration of anesthesia or other treatment.
The cutaneous electrode bore serves as a guide for the initial placement of the needle at the registration point and for guidance of the needle travel path toward the target nerve. Maintaining the dermal layers in a depressed or indented state by continued pressure on the cutaneous electrode serves to fix the location of the target nerve.
From the foregoing compendium, it will be appreciated that it is an aspect of the present invention to provide a nerve stimulator needle guidance system of the general character described which is not subject to the disadvantages of the antecedents of the invention.
It is a feature of the present invention to provide a nerve stimulator needle guidance system of the general character described which simplifies the administration of nerve blockade anesthesia.
A consideration of the present invention to provide a nerve stimulator needle guidance system of the general character described which increases the likelihood of the successful administration of regional anesthesia with a single needle pass.
A feature of the present invention is to provide a nerve stimulator needle guidance system of the general character described which noninvasively locates the entry point of a nerve stimulator needle.
To provide a nerve stimulator needle guidance system of the general character described which is well suited for conventional sterilization techniques is a further consideration of the present invention.
An aspect of the present invention is to provide a nerve stimulator needle guidance system of the general character described which decreases the likelihood of anesthesia administration complications resulting from errant needle passes.
An additional consideration of the present invention is to provide a nerve stimulator needle guidance system of the general character described with increased nerve block success levels.
A further feature of the present invention is to provide a nerve stimulator needle guidance system of the general character described with reduced patient discomfort attributable to multiple needle passes.
To provide a nerve stimulator needle guidance system of the general character described with increased safety is a further aspect of the present invention.
Yet a further consideration of the present invention is to provide a nerve stimulator needle guidance system of the general character described which minimizes the time required to achieve a nerve blockade.
To provide a nerve stimulator needle guidance system of the general character described which is simple to use is a further aspect of the present invention.
A still further aspect of the present invention is to provide a nerve stimulator needle guidance system of the general character described which is economically disposable after a single usage.
Another feature of the present invention is to provide a nerve stimulator needle guidance system of the general character described which lends itself to economical mass production fabrication.
Other aspects, features and considerations of the present invention in part will be obvious and in part will be pointed out hereinafter.
With these ends in view, the invention finds embodiment in certain combinations of elements, arrangements of parts and series of steps by which the said aspects, features and considerations and certain other aspects, features and considerations are attained, all with reference to the accompanying drawings and the scope of which will be more particularly pointed out and indicated in the appended claims.